1. Field of the Invention
This invention relates in general to improvements in a coated body which is provided by a substrate and a hard coating disposed on the substrate.
2. Discussion of the Related Art
There is widely used a machining tool, such as a rotary cutting tool (e.g. drill and end mill), a non-rotary cutting tool (e.g., lathe tool) and a non-cutting tool (e.g., cold-forming tool, thread rolling tool and fluteless tap), which is used to machine a workpiece by moving at least one of the machining tool and the workpiece relative to the other. There has been proposed a technique for covering a substrate of the machining tool with a hard coating for increasing wear resistance and durability of the machining tool. JP-B2-3232778 (publication of Japanese Patent issued in 2001) discloses a shot blasting operation, which is carried out after formation of a hard coating on a tool substrate, for releasing residual or internal stress from the formed hard coating.
Although the coated machining tool exhibits excellent wear resistance and durability, there is still a demand for further improved wear resistance and durability of the machining tool, for satisfying a requirement for further increased machining efficiency and further prolonged tool life.